How to Control Pests & Disease

Diseases and insects can ruin a plant, and all your hard work. So it’s important that you know what to do to help protect your garden. This guide will help you identify the main culprits, treat the diseases, and keep your garden in good health.

Understanding pesticides

Pesticides are chemicals that are broken down into three main segments:

• Fungicides are chemicals that are used to kill fungus and bacteria infections.
• Insecticides are used to specifically target and kill insects.
• Herbicides are used to kill undesirable plants or “weeds”. Some herbicides will kill all the plants they touch, while others are designed to target one species.

Control methods

Here are some control methods for pests and diseases.

Cultural Control

The best way of controlling pests and disease in your garden without using insecticides or fungicides is to have excellent garden hygiene:

• Keep your garden clear of long grass and weeds as they often harbour pests.
• Diseased plants, fallen leaves, fruit, and pruning wood should be removed as they harbour spores which can reinfect your plants.
• Plants suffering from moisture stress (either too little or too much) are more susceptible to infections and infestations.
• Choose disease resistant varieties of plants and choose plants suited to your local soil and conditions.
• A well-fed healthy plant is less likely to get attacked by diseases or insect pests

Mechanical control

Tree bands: These easy to use, eco-friendly and poison free traps will stop pest insects from climbing your trees from the soil to lay eggs and feed; damaging your trees and fruits. The sticky surface acts as a barrier, stopping these pests in their tracks!

Insect sticky traps: The bright yellow colour of the traps attracts damaging insects away from your plants, permanently trapping them in the sticky coating once they land.

Pheromone traps: These attract male moths like the Guava or Codling Moth, and helps break their breeding cycle. Trapping the male Moth will reduce breeding fewer eggs laid means fewer maggots to attack your fruit.

Slug and snail traps: Fill the dishes with snail lure (or beer) to attract slugs and snails. They will then drown themselves.

Natural & Biological Control

Natural predators: Introduce natural enemies to pests. Birds feed on insects, while lacewings feed on aphids and whitefly. Ladybirds, frogs, lizards, spiders, and wasps all feed on insects. Welcome and conserve as many of these creatures as possible in your garden. For example, a single frog can eat as many as 10,000 insects in a three-month period.

Companion planting: This is a natural form of pest control. Include herbs that deter garden pests (e.g. chives and garlic planted under roses deter aphids; marigolds combat whitefly) and shrubs, which attract insect-eating birds. Click here for a detailed list of companion plants.

Chemical Control

Fungicides and pesticides are the quickest and most effective method of preventing and controlling pests and diseases. Insecticides and fungicides are chemicals, so it is extremely important to understand how to use them properly, and keep safe.

• A guide to the toxicity of a product can be found on the front label of the container. Those marked ‘Poison’ are the most toxic compounds. Slightly less toxic are those marked ‘Caution’. Those products which have low toxicity with a higher degree of safety for humans are simply marked, ‘Keep out of Reach of Children’ and/or ‘Read Safety Directions’ and/or nothing.
• Wear rubber gloves and a mask when spraying.
• Avoid contact with exposed parts of the body, especially eyes. Avoid breathing in spray or dust. If you splash anything on you wash with clean water immediately.
• Keep children and pets away when using chemicals.
• Do not spray in windy conditions. Coverage will be spotty and spray drift can be dangerous.
• Spray in the early morning or late afternoon. Midday spraying can result in serious burning of plant tissue by the sun.
• Store chemicals in a cool, dry, safe place away from children and pets.
• Some chemicals do not mix. Use ready to use products to make life simple if you don’t like diluting your own sprays.
• Use a separate sprayer for fertilising, insecticides, fungicides, and herbicides. Make sure these are labelled.
• Set aside a shelf or garden bench, preferably outside, to mix garden chemicals.
• To help protect pollinator insects like bees, do not spray plants in flower, and spray in early morning or in the evening when these insects are not active.
• Food crops need different sprays compared to ornamentals. Sprays and dusts for edible crops are prepared to dissipate quickly.
• Always follow label instructions and time your last spray before harvest carefully. Wash fruit and vegetables before eating.

Withholding Period

• The withholding period is the time that must pass after application of a pesticide before the crop can be harvested and eaten.
• If a product registered for application to fruit or vegetables does not show a withholding period it means that the fruit or vegetables can be eaten straight away.
• All sprays that can be used on edibles will have a withholding period stated, some may say 0 days withholding, not showing a withholding means the product can only be used on non edibles.

Click here to download the pdf guide with more information on the common pests and diseases and how to control them.